Diamondhead CLASSIC Flip-Up Front Combat Sight, M4 Diamondhead"s CLASSIC Flip-Up Front Sight"s design incorporates the traditional "M4" style upper housing on a Diamondhead Premium sight base. The CLASSIC sight has a very low folded height of 0.435" and is compatible with all Mil. Std. M1913 Picatinny rail systems. Features: - Traditional "M4" style upper housing - Flips up quickly for rapid deployment - Folds down with the push of a button - Secure and accurate elevation adjustment - Accepts all standard A2 front sight posts - Locking system ensures sight stays up securely and remains zeroed in combat situations - Easy installation with proprietary clamping system, providing secure attachment to all Mil. Std 1913 Picatinny Rails - Mil. Spec. stainless steel and Type 111 black anodized 6061 T6 aircraft aluminum construction - Combat Durable